Primary mesenteric tumours are rare, with case reports scattered throughout the literature. Gastrointestinal stromal tumours (GISTs) are mesenchymal neoplasms which affect the gastrointestinal tract, most commonly occurring in the stomach and proximal small intestine, rarely occurring outside the GI tract (extra-gastrointestinal stromal tumours – EGISTs) in places such as the mesentery.1 GISTs themselves are rare and estimated by one study to have an annual incidence rate of only 0.00068%.2 Less than 5% of these GISTs are EGISTs.3 This case report highlights a particularly mobile EGIST...

My patient is a 65-year-old gentleman who first presented with epigastric abdominal pain. A diagnostic laparotomy which was acted on a CT Abdomen showing a small bowel mass was negative. The patient then returned the following year with similar epigastric pain. A repeat CT Abdomen then demonstrated a large mass in the right iliac fossa while a follow up MRI Abdomen carried out 11 days later demonstrated that the same mass had moved to the left upper quadrant. Other investigations including gastroscopy and Gastrografin small...

Figures 1, 2: CT Abdomen demonstrating a large right iliac fossa mass which is predominantly solid with locules of gas. Figures 3, 4, 5: MRI showing the same large, lobular mass which has now changed position from the right iliac fossa to the left upper quadrant, displaying low signal intensity on T1 and high signal intensity on T2 with irregular enhancement. Figure 6: The large mass displaying moderate 18F-Fluorodeoxyglucose (FDG) avidity on a PET/CT scan. Figures 7, 8: Histopathology results from the surgical resection confirming...

The patient’s CT, MRI and PET images were consistent with the typical findings of a GIST tumour. The change in the tumour’s position on the MRI suggested mobility within the patient’s mesentery, which would also explain the previous negative diagnostic laparotomy. This was subsequently confirmed on the emergency laparotomy and histological findings. Primary mesenteric tumours are rare, as are EGISTs and should be considered when a tumour changes position on serial images.

Dr Joshua Wei Liang Yip MBBS ICU Registrar, Port Macquarie Base Hospital (NSW, AU) Radiology Honorary Medical Officer, Royal North Shore Hospital (NSW, AU) Contact: [email protected]

Miettinen M, Lasota J. Gastrointestinal stromal tumors – definition, clinical, histological, immunohistochemical, and molecular genetic features and differential diagnosis. Virchows Arch. 2001;438(1):1-12. Ma GL, Murphy JD, Martinez ME, Sicklick JK. Epidemiology of gastrointestinal stromal tumors in the era of histology codes: results of a population-based study. Cancer Epidemiol Biomarkers Prev. 2015;24(1):298-302. Fagkrezos D, Touloumis Z, Giannila M, Penlidis C, Papaparaskeva K, Triantopoulou C. Extra-gastrointestinal stromal tumor of the omentum: a rare case report and review of the literature. Rare Tumors. 2012;4(3):e44.